Heavy-duty engine starter gearing



March 7, 1950 D. L. MILLER 2,500,132

HEAVY DUTY ENGINE STARTER GEARING Filed Aug. 9, 1948 2 Sheets-Sheet l 1915 14161562 6 133 a I L 4 y- \1\ \Z\ 4 17 7-1 1N VEN TOR.

T T ORNE Y March 7, 1950 D. I... MILLER 2,500,132

HEAVY DUTY ENGINE STARTER GEARING Filed Aug. 9, 1948 2 Sheets-Sheet 2 1 39141647 Q2441 I I 0*. 1&6

INVENTOR. r' v WITNESS O o am. 075647;; I M

ORNE' Y Patented Mar. 7, 1950 HEAVY-DUTY ENGINE STARTER GEARING Donald L. Miller, Elmira, N. Y., assignor to Benclix Aviation Corporation, a corporation of Delaware Application August 9, 1948, Serial No. 43,214

5 Claims.

The present invention relates to heavy duty engine starter gearing, and more particularly to that type of transmission in which a motor driven pinion is shifted manually or by other extraneous means into and out of mesh with an engine gear.

Manually shiftable gearing of various kinds is widely used for starting internal combustion engines of low and intermediate power, but when gearing of this type is used to start large engines such as Diesels for industrial or locomotive power plants, difliculty has been encountered in so designing the shifts as to provide satisfactory operative life. In particular, it has been found that the usual forms of over-running clutch, when embodied in a heavy duty shift, produce unit pressures between the parts which are beyond the safe working stresses of the material available.

It is an object of the present invention to provide a novel heavy duty starter gear which is structurally adequate for the purpose and is free from dangerously large localized pressures.

It is another object to provide such a device which is simple in construction, reliable in operation, and economical to manufacture.

It is another object to provide such a device which incorporates means for limiting the torque transmitted there-through to a predetermined maximum.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention;

Fig. 2 is a similar view showing the parts in cranking position;

Fig. 3 is a detail in perspective of the spring frictional retarding element for the over-running clutch;

Fig. 4 is a view similar to Fig. l of a second embodiment of the invention;

Fig. 5 is a section taken substantially on the 7 line 5-5 of Fig. 4; and

Fig. 6 is a view similar to Fig. 1, of a third embodiment of the invention.

In Fig. l of the drawing there is illustrated a power shaft I on which a sleeve 2 having a radial flange 3 is slidably but non-rotatably mounted as by means of splines 4. A pinion 5 is slidably journalled on the power shaft as by means of a bushing 6, for longitudinal movement into and out of mesh with an engine gear 1. A driven 55 clutch member 8 is fixedly mounted on the end of the pinion 5 as indicated at 9, and a barrel member H is arranged to surround the driven clutch member and the flange 3 of the sleeve 2. Said barrel has an inwardly extending portion l2 at one end forming a thrust bearing for the driven clutch member 8 and is slidably but nonrotatably connected to the flange 3 at its other end by means of lugs [3 on said flange slidably mounted in longitudinal slots I4 in the barrel.

A driving slip clutch member I5 is mounted in the barrel l i and non-rotatably connected thereto by means of lugs l6 extending into the slots I4. Spring members I! in the form of elastic discs are interposed between the flange 3 of sleeve 2 and the driving slip clutch member l5, said springs being maintained under com pression by a lock ring I8 seated in a groove l9 in the barrel ll.

Driving slip clutch member I5 is provided with inclined torque transmitting teeth 2|, and an intermediate clutch member 22, journalled on an extended portion 23 of the pinion bushing 5, is provided with similar inclined torque transmitting teeth 24 adapted to cooperate with the teeth 2|. The intermediate clutch member 22 is also provided with overrunning clutch teeth 5 adapted to cooperate with similar overrunning clutch teeth 26 formed on the adjacent side of the driven clutch member 8.

Means are provided for moving the intermediate clutch member 22 into engagement with the driven clutch member 8 when rotation is to be transmitted from the power shaft to the pinion. As here shown, this means comprises an elastic split ring member 21 (Fig. 3) which is seated and bears frictionally in a groove 28 in the extension 23 of the pinion bushing, said ring having a slot 29 formed in one end thereof. A pin 30 is fixedly mounted in any suitable manner in the intermediate clutch member 22, and is provided with an inwardly extending portion 3| at its end which projects into the slot 29 of ring 27 so that the ring and pin form a longitudinally slidable frictional connection between the intermediate clutch member 22 and the pinion 5. Rotation of the driving clutch member l5, when the pinion is stationary, thus causes the inclined teeth of the driving clutch member to move the intermediate clutch member into engagement with the driven clutch member 8.

In order to facilitate the longitudinal movement of the intermediate clutch member into and out of engagement with the driven clutch member, the slot 29 in the ring member 21 is preferably inclined or skewed with respect to the axes of the shaft as shown in Fig. 3. The inclination of the slot 29 is such that rotary movement of the intermediate clutch member 22 and pin 38 in a forward direction, as indicated by the arrow (a), with respect to the ring 21, will tend to move the intermediate clutch member into engagement with the driven clutch member 8 so as to cause engagement of the over-running clutch teeth 25, 26; whereas acceleration of the pinion, frictionally transmitted to the ring 21, will cause the pin 30 to draw the intermediate clutch member 22 out of engagement with the driven clutch member 8.

Means for shifting the sleeve 2 with its associated parts, longitudinally on the shaft I in order to move the pinion 5 into and out of mesh with the engine gear I is provided comprising a shift collar 33 slidably mounted on the sleeve 2, and yieldably held against a lock ring 34 by a spring 35 bearing against the flange 3. A shift fork 36 which is arranged to be operated either manually or by any other suitable means is provided with rollers 31 for engaging and actuating the shift collar 33.

In operation, shifting of the sleeve 2 to the right in Fig. 1 by the shift fork 36 causes the pinion 5 to mesh with the engine gear i as shown in Fig. 2. Energization of the power shaft by closure of the starting switch, not illustrated, then causes rotation of the sleeve 2 which is transmitted through the barrel to the driving clutch member i5. This rotation is transmitted through the teeth 2|, 24 to the intermediate clutch member 22, and the initial rotation of the latter causes the end 3| of pin 30 to traverse the inclined slot 29 of the ring 21, thus moving the intermediate clutch member 22 longitudinally to engage the teeth 26 of the pinion driven clutch member 8. Torque is then transmitted to the pinion 5 to rotate the engine gear. If the initial load on the gearing exceeds a predetermined maximum, the inclined teeth 2|, 24 of the clutch members I5, 22 are wedged apart, further compressing the springs |7 until the clutch teeth slip over each other so as to prevent the transmission of excessive loads.

When the engine starts, the acceleration of the pinion 5 is transmitted frictionally to the ring 27 which thereupon operates to withdraw the intermediate clutch member 22 from the driven clutch member 8 so as to permit the pinion to overrun freely. This condition persists as long as the engine remains self-operative while the pinion is maintained in mesh with the engine gear. If the engine stalls, as soon as the rotational speed of the pinion falls below that of the intermediate clutch member 22, the spring 21 again becomes efiective on the pin 3|? to cause reengagement of the overrunning clutch teeth 25, 26. When the engine is reliably self operative, the parts are returned to idle position by means of the shift fork 38.

In the embodiment of the invention illustrated in Figs. 4 and 5, the parts are generally similar to those in the first embodiment described and are similarly numbered. In this case, however, an adjusting ring 38 is threaded on the exterior of the barrel H as indicated at 39 in order to vary the initial compression of the clutch springs II.

In this embodiment also, the retarding means for controlling the intermediate clutch member 22 is in the form of the spring ring 4| fixedly anchored at one end on the periphery of the driven clutch member 8' as shown in Fig. 5, and bearing frictionally in the interior of a sleeve 42 fixed in any suitable manner on the periphery of the intermediate clutch member 22. Light compression springs 43 are interposed between the overrunning clutch members 22' and 8 to normally hold them apart. Springs 43 are preferably spaced and alined by means of pins 40 mounted in a ring 50 which bears frictionally on the end of pinion 5, the free ends of the pins being slidably mounted in the intermediate clutch member 22'.

In the operation of this embodiment of the invention rotation of the intermediate clutch member 22' from the power shaft is initially resisted by the retarder spring 4| so that the inclined teeth 2|, 24 of the overload slip clutch cause traversal of the intermediate clutch member 22 to the right to close the overrunning clutch teeth 25, 26, whereupon cranking takes place as in the embodiment first described. When the engine starts, and the pinion 5 overruns, separation of the overrunning clutch teeth 25, 26 is assisted by the springs 43.

In the embodiment of the invention illustrated in Fig. 6 the structure is substantially similar to that shown in Figs. 4 and 5 and the parts are similarly numbered, except for the intermediate clutch element. As here shown, this clutch element is formed in two parts which are threaded together. The first part 44 has inclined teeth 45 for engaging the inclined teeth 2| of the driving clutch member, and an extended portion in the form of a hollow screw shaft 46. The second part is formed as a nut 47, threaded on the screw shaft and has overrunning clutch teeth 48 arranged to engage the similar teeth 26 of the pinion flange member 8'. A retarder ring 4| similar to the retarder 4| in Figs. 4 and 5 is anchored to the periphery of the driven clutch member 8 and bears frictionally in the interior of a ring 42 fixed on the periphery of the nut 41.

In the operation of this structure, initial closure of the overrunning clutch teeth 48, 26' is brought about by the screw-jack action of the screw shaft 46 and nut 41, and disengagement of the overrunning clutch is similarly brought about when the pinion overruns the power shaft by virtue of the frictional connection provided by the spring 4|. The operation is otherwise the came as previously described.

Although certain embodiments of the invenion have been shown and described in detail, it will be understood other embodiments are possible and that various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In a starter for internal combustion engines, a power shaft, a flanged sleeve splined thereon, means for shifting said sleeve on the power shaft, a pinion slidably journalled on the power shaft for longitudinal movement into and out of mesh with a gear of an engine to be started, a driven clutch member fixedly mounted on the pinion, a barrel member non-rotatably connected at one end to the flange of said sleeve and enclosing and providing a stop for the driven clutch member at its other end; a driving clutch member splined in the barrel having teeth with inclined torque transmitting surfaces, an intermediate clutch member having teeth cooperating with those of the driving clutch member, means yieldingly resisting the wedging apart of said clutch members due to the transmission of torque therethrough, said intermediate clutch member and the'driven clutch member having inter engaging overrunning clutch teeth; and means whereby the transmission of torque through the intermediate clutch member from the power shaft causes the intermediate clutch member to engage and drive the driven clutch member.

2. An engine starter as set forth in claim 1 including further, means frictionally connecting the intermediate clutch member to the pinion.

3. A starter as set forth in claim 2 in which said frictional means includes an inclined connection operative to bring the intermediate clutch member and pinion into-clutching engagement when the intermediate clutch member rotates faster than the pinion, and to separate said members when the pinion overruns the intermediate clutch member.

4. In a starter gear, a power shaft, a sleeve splined thereon, a pinion slidably journalled on the shaft for longitudinal movement into and out of mesh with a gear of an engine to be started, and means for transmitting rotation from the sleeve to the pinion including an overload release clutch having teeth arranged to slip over each other when a predetermined load is exceeded; a dental type overrunning clutch, a barrel member enclosing both the clutches, and means including yielding means cooperating with said barrel to compress the overrunning clutch and resist slippage of the overload release clutch.

5. In a starter gear, a power shaft, a sleeve splined thereon, a pinion slidably journalled on the shaft for longitudinal movement into and out of mesh with a gear of an engine to be started, and means for transmitting rotation from the sleeve to the pinion including a barrel member splined to the sleeve at one end and having a swivel connection with the pinion at the other end, a driving clutch member having teeth with inclined torque-transmitting sides splined in the barrel and journalled on the power shaft, an intermediate clutch member having cooperating inclined teeth slidably journalled on the power shlaft, a dental overrunning clutch connection between the intermediate clutch member and the pinion, and means including a yielding member resisting slippage of the driving clutch and at the same time compressing the overrunning clutch connection.

DONALD L. MILLER.

REFERENCES CITED UNITED STATES PATENTS Name Date Jackson et al. Dec. 27, 1932 Number 

